Work Power

A kid throws a ball with a force of 70N over 1.1 meters. How much work did he do?

• 77 joules

• 70 joules

• 7.7 joules

• 11 joules

The formula for work is

• work/time (P = W/t)

• force × distance (W = Fd)

• distance/time (s = d/t)

• mass × acceleration (F = ma)

Tags

NGSS.MS-PS3-5

The formula for power is

• work/time (P = W/t)

• force × distance (W = Fd)

• distance/time (s = d/t)

• mass × acceleration (F = ma)

Use one of these equations to answer this question (W = Fd) and (P = W/t): When Aang fights Ozai, he wields 100,000 Joules in 25 seconds. What is his power?

• 4,000 J/s (Watts)

• 250,000 J/s (Watts)

• 125,000,000 Newtons

• 2,000,000 Joules

Tags

NGSS.HS-PS3-1

The rate at which work is done is ____.

• power

• force

• efficiency

• momentum

You do 90 joules of work in 30 seconds. How much power have you generated?

• 30 watts

• 3 watts

• 120 watts

• 270 watts

Answer explanation

Power is calculated as work done divided by time. Here, power = 90 joules / 30 seconds = 3 watts. Therefore, the correct answer is 3 watts.

Which of these is a measurement of power?

• 100 joules

• 100 watts

• 100 meters per second

• 100 hertz

You move an 8-newton weight five meters in 4 seconds. How much power have you generated?

• 160 watts

• 10 watts

• 6.4 watts

• 17 watts

Answer explanation

Power is calculated as work done over time. Work = force x distance = 8 N x 5 m = 40 J. Power = work/time = 40 J / 4 s = 10 watts. Thus, the correct answer is 10 watts.

Which is the result of using a more powerful motor to run an elevator?

• The same amount of work is done in less time.

• Less work is done in the same amount of time.

• The same amount of time is needed to move the same distance.

• A longer time is needed to move a shorter distance.

The equation for POWER is

• power = mass x time

• power = work / time

• power = time / work

• power = work x time